Two side sharpening of cutters



J1me 1968 J. w. IJ. HEIJNIS 3,3891506 TWO SIDE SHARPENING OF CUTTERS Filed Sept. 2, 1965 2 Sheets-Sheet 1 INVENTOR. JAMES WATT lJSBRAND HEIJNIIS ATTORNEY June 25, 1968 J. w. IJ. HEIJNIS 3,389,506

TWO SIDE SHARPENING OF CUTTERS Filed Sept. 2, 1965 2 Sheets-Sheet 2 FIG. 2

FIG. 4

I INVENT OR. JAMES WATT IJSBRAND HEIJNIS BY W ATTORNEY v United States Patent 3,389,506 TWO SIDE SHARPENING OF CUTTERS James W. lj. Heijnis, Arnhem, Netherlands, assignor to American Enka Corporation, Enka, N.C., a corporation of Delaware Filed Sept. 2, 1965, Ser. No. 484,634 Claims priority, application Netherlands, Sept. 19, 1964, 6410973 2 Claims. (Cl. 5l--3) ABSTRACT OF THE DISCLUSURE Apparatus for honing, grinding, lapping, polishing and/ or sharpening cutting devices comprising a pair of relatively adjustable rotatable members in frictional intermeshing engagement with each other acting to form a throat into which the cutting device such as a knife, blade or the like to be sharpened may be inserted.

The present invention relates to an apparatus for the lapping of knives and comprises two grinding members which are moveable relative to each other and together form :a throat into which a knife edge may be fitted for sharpening.

In the art of cutting fibers from a tow of synthetic fila ments, there is always present the requirement for knives having extremely smooth and sharp edges. For example, if a tow of a polyamide or polyethylene terephthlate is cut into fibers, the edges of the cutting knives used often become so blunt that after only a short time cutting becomes very difiicult. The energy required to cut the tow into fibers becomes high as the knife edge dulls and consequently the quality of the cut fibers is reduced considerably as a result of frayed and fused ends of the fibers. Fibers having such ends are dilficult to process because the frayed or fused ends tend to cohere and sometimes become fused to one another. These unsatisfactory fiber ends can be attributed to the high cutting energy which is converted into heat and thus causes a sharp increase in the temperature of the fiber ends. This temperature is, in some cases, above the melting point of the fiber material.

It is known that the aforedescribed high cutting energy is due to imperfections of the cutting blade such as bluntness, an overly large radius of curvature of the cutting edge, and extreme roughness of the blade sides. Consequently, it becomes important that the cutting knives be made as sharp and smooth as possible and the formation of burrs be avoided as much as possible.

In the past apparatus used for sharpening knives of the type employed in the aforementioned cutting operation have been constructed using two smooth, disc-shaped cylindrical grinding wheels. A knife could be sharpened by placing its edge between these wheels and reciprocating it in a direction parallel to the axis of rotation of said wheels.

Using this type of known apparatus, it has been difficult to sharpen cutters, knives and like devices to a degree required in commercial textile severing operations of the above kind. This is due in part to the fact that as the cutters are sharpened, some force must be exerted in pressing a side of the cutter or knife blade against a lapping, grinding, or like sharpening member in order that material may be removed therefrom. As the blade of the ice cutter or knife remains in a fixed position against the lapping, grinding, or like sharpening member and force is exerted on the blade while in that position for a given period of time, such force tends to disadvantageously bend back the cutting edge of the blade thus forming a burr thereon. Unless the transverse reciprocating movement of the blade across the grinding, lapping and like sharpening members is perfectly uniform and the transverse blade speed and force exerted thereon are carefully controlled in relation to the rotational speed of the members, burring is found to be extremely difiicult to avoid.

Employing only the prior art type of sharpening apparatus described above, some cutting operations have provided for the continuous exchange of knives in order to continuously cut with a blade having an acceptable sharpness and smoothness. However, the exchanging of knives in the cutter is a time consuming operation which is attended with a considerable loss of production and is therefore undesirable.

Accordingly, it is an object of the present invention to provide a new and improved apparatus for the lapping of knives which is capable of sharpening blades to a degree of sharpness and smoothness heretofore unattainable using apparatus of the prior art.

It is another object of the invention to provide a new and improved apparatus for the lapping of knives which eliminates the continuous and frequent exchanging of knives in certain cutting operations which require blades having a long edge life.

These and other objects of the invention will become more fully apparent in the following description of the accompanying drawings wherein:

FIGURE 1 shows an elevation view, partly in section, of the apparatus of the present invention;

FIGURE 2 shows a plan view of the spiral-grooved horizontal cutting member of FIGURE 1;

FIGURE 3 schematically shows the disposition of the blade being sharpened relative to the sharpening members; and

FIGURE 4 is a cross-sectional view of a blade to be sharpened.

Briefly described, the present invention comprises a pair of rotatable sharpening members in frictional engagement to form a throat into which a knife edge may be inserted and means for providing relative movement between the sharpening surfaces of said members in a direction longitudinal of the knife edge to be sharpened. The lapping or sharpening members which are moveable relative to each other have winding rims and grooves on the surfaces thereof of rectangular cross-section. The winding rims and grooves of the rotating members intermesh as they rotate and form a throat angle which is equal to the blade angle of the knives to be lapped. As the cutting edge of a knife blade is sharpened any tendency toward burr formation is counteracted by a relative movement between the rims of the rotating members and the blade which is in longitudinal direction of the blades cutting edge. All points along the cutting edge will continuously be subjected to oppositely directed changes in pressure exerted by the intermeshing rims and grooves of the cutting members. As a result, any burr formed on the cutting edge is lappe/l away before it has had a chance to become sizeable.

Referring now in detail to the drawings, there is shown in FIGURE 1 a base plate 1 on which a driving motor 2 is mounted.

Supporting column 6, carrying hollow cylindrical supporting member or bushing 7, is also mounted on base plate 1. Cylindrical member 7 supports one end shaft or spindle 8, the axis of which is essentially perpendicular to the axis of drive shaft 3. Said another way, the axis of spindle 8 can be visualized as being directed toward a hypothetical continuation of the axis of motor drive shaft 3.

Spindle 8 is mounted for rotary movement in two ball bearings 9 and 10. Bearings 9, 19 and conical member 11 are all secured to spindle 8 by clamping ring 12. An abrasion resistant ring 13 seals the space in which the bearings are located.

At the end of conical member 11 nearest the drive shaft (shaft 3), there is provided beveled gear 14 mounted for rolling contact with a geared, upstanding rim of the disc 5. Teeth 15 of the rim are in driving engagement with beveled gear 14, and are frictiona-lly affixed to and slidable in the conical member 11. Hence, in a plan view, helical upstanding rim or rib 18 to be discussed fully below is positioned outermost, and teeth 15 are placed innermost on the disc, respectively. Two adjusting pins 15 and 17 are attached to beveled gear 14 and drive shaft 3, respectively, and serve to properly adjust the relative positions of gear 14 and engaging teeth 15 of the upstanding rim. As a consequence of this facility, the relative positions of members and 11 may be changed, if desired.

The flat disc 5 is provided with continuous rectangular upstanding rims or ribs 18 which intermesh, with little clearance, in the single helical rectangular recess groove 19 in the conical member 11. The groove 19 in the conical member 11 runs along a helical line having a constant pitch and this groove engages at least four complete, equidistant, spiraling rims 18 as can best be seen in FIGURE 2. In other words, helically threaded cone 11 intermeshes and coacts with the helically threaded disc 5 at A.

The number of teeth of the gear 14 is approximately one-fourth of the number in the rim of teeth 15. Upon rotation of the drive shaft 3 the disc 5 will be rotated by way of the engaging means 4 and the conical member 11 will be rotated on the spindle 8 due to the engagement of teeth with the gear 14. The rims and grooves 18 and 19 are so shaped that they permanently intermesh.

Provided under the disc 5 is a collecting vessel 20 into which enters a plurality of channels 21 running from the top of the disc downward. When a liquid-carried abrasive is fed to the upper side of the conical member 11 or the rims 18 of the disc 5, the surplus abrasive will pass through the channels 21 and may be collected in the vessel 20. A round collar 23 on the disc 5 prevents the abrasive from getting between the gear 14 and the rim of teeth 15.

FIGURE 2 shows a plan view of the disc 5. The rims 18 on disc 5 run along four equidistant spiralling lines, and each of the grooves between these rims intermeshes with the helical rim on the cone 11.

FIGURE 3 shows the disposition of the conical member 11 and the disc 5 and their relationship to a blade 22 which is to be sharpened. The rims and grooves 13 and 19 respectively intermesh at an angle a forming a throat into which blade 22 is inserted. The blade 22 is positioned on the side of the conical member 11 where the motion of the disc 5 and the conical member 11 is directed against the cutting edge of the blade.

FIGURE 4 shows the blade 22 on an enlarged scale and in cross-section. The blade angle of the knife is a and the cutting edge is lapped alternately by a rim of the conical member 11 and a rim of the disc 5. By appropriately choosing the width of said rims it is possible to prevent the formation of burrs on the blade. The smaller the width, the higher the rate at which each point of the cutting edge is lapped alternately on its upper side and underside by the upper and lower rims, respectively. Rim

widths up to 10 mm. have been found to be sutficiently narrow while rim widths of approximately 6 mm. are to be preferred.

With the members 4 and 11 running at an average circumferential speed of 1 meter per second, it was observed that a complete lapping of certain blades can be accomplished in about 30 seconds. The sharpness of these knife blades was then tested by measuring the energy required for cutting a polyamide filament tow. Using the apparatus as described above blunt knives could be sharpened to produce a blade which used between 7.5 and 10 ergs per denier in cutting the tow. As is well known in the art, a blade requiring only this small amount of cutting energy for cutting a polyamide filament tow is considered sharp.

To aid in the lapping treatment an abrasive is frequently used. This abrasive is usually in the form of a liquid or thin paste and is normally app-lied at the point where the lapping takes place. It will be observed in the embodiment of FIGURE 1 that with the disc 5 in the horizontal position the abrasive will not readily flow away from the sharpening surfaces.

If desired a plurality of identical cones 11 may be used with the same disc 5 and in this way it becomes possible to simultaneously lap a plurality of blades, depending upon the number of cones used. However, it has been found advisable to have the disc cooperate with a single cone if blades are required to be finished to extremely fine limits.

If desired, a blade may be reciprocated relative to the sharpening surfaces of members 5 and 11 in a direction longitudinal of the cutting edge of the blade. For this purpose a special mechanism (not shown) may be provided to impart reciprocating motion to the blade.

It is also possible to move the blade and the sharpening rims relative to each other without motion being communicated to the knife itself. This is made possible according to the invention since the sharpening rim on the cone or cones runs along a single helix and the sharpening rims on the disc run along a plurality of equidistant spiralling lines.

Various other modifications of the invention may be made without departing from the spirit and scope thereof. For example, the speeds of the disc and the cones may be controlled independent of each other depending upon the type of blade to be sharpened, the degree of sharpness required and other factors related to these speeds. If it is desired to have the disc and the cones running independent of each other, an external mechanism may be provided for speed control purposes and the gear coupling between cone and disc may be eliminated. For many applications however it is preferred to use a driving system for the apparatus for moving the cone against the knife edge at a speed higher than that of the disc.

It should be understood that the invention may be practiced otherwise than as specifically described without departing from the spirit and scope of the following appended claims.

What is claimed is:

1. Apparatus for the lapping of knives comprising,

(a) a pair of rotatable sharpening members, each having exterior sharpening surfaces which come together at an angle to form a throat into which a knife blade may be inserted, said angle being equal to the blade angle of the knives to be lapped;

(b) means for moving said surfaces along said blade in a direction longitudinal to the edge of said blade;

(0) said rotatable, sharpening members having a plurality of spiral'led rims and grooves thereon intermeshed to form said throat;

-(d) one of said members is a horizontal disc having a plurality of separate rims and grooves thereon running on a plurality of equidistant spiralling lines; and

(e) the other of said members is a cone having a rim thereon running along a single helix and being intermeshed with said rims and grooves on said disc.

5 6 2. Apparatus according to claim 1 wherein said rims 1,946,311 2/ 1934 Corneau 5180 on both discs and said cone run along a plurality of cqui- 2,153,275 4/ 1939 Schulze 51111 X distant circles, 2,164,959 7/ 1939 Steiner 51-80 2,290,964 7/1942 Hill 5180 References Cited UNITED STATES PATENTS 1,438,098 12/1922 Delzell 51-80 1,918,111 7/ 1933 Kohlmiller 51-80 LESTER M. SWINGLE, Primary Examiner.

FOREIGN PATENTS 284,010 1/1928 Great Britain. 

